It was known in the prior art to combine various oils and greases with powders of polymeric fluorocarbons in order to generally increase the lubricating quality and durability of the lubricant. However, present improved lubricating composition and method are not known. U.S. Pat. No. 3,664,956 granted May 3, 1972 to Messina, et al, discloses a lubricant comprising polytetrafluoroethylene in combination with polysiloxanes and a grease composition.
Typically, these oil and grease based lubricants contained other additives in addition to polymeric fluorocarbons so as to create or improve a characteristic of the lubricating composition.
For instance, U.S. Pat. No. 4,224,173 granted Sept. 23, 1980 to Reick, discloses the use of a lubricating oil containing polytetrafluoroethylene (PTFE) particles and a fluorochemical surfactant for stabilizing the oil-PTFE dispersion and reducing volatilization losses during use of the lubricant in an internal combustion engine.
In U.S. Pat. No. 3,723,317 granted Mar. 27, 1973 to Ulery, lubricating greases are disclosed which comprise a fluorinated polyester, a base oil, PTFE and a triazine compound for improving anti-corrosive and air oxidation resistance qualities of the lubricant.
The prior art of U.S. Pat. No. 3,933,656 granted Jan. 20, 1976 to Rick, also discloses a lubricant comprising a base oil intermixed with a dispersion of PTFE particles and a silane which, acting as a charge neutralizing compound, prevents a clumping together of the PTFE particles in suspension.
In order to enable the lubricant dispersions to retain their structural integrity and stability under extreme pressure and temperature and sheer stress conditions and to prevent the settling out of suspended particles such as PTFE, the prior art typically added thickeners such as fatty acid soaps, metal salts, mineral diatoms and organic polymers. U.S. Pat. No. 3,493,513 granted Feb. 3, 1970 to Petriello, discloses a lubricating grease and oil composition comprising a base oil PTFE particles and a selected amount of polyethylene added as a thickener. U.S. Pat. No. 3,639,237 granted Feb. 1, 1971 to Curtis also relates to a lubricant grease which comprises a base oil, PTFE powder, and further comprises colloidal asbestos and other inorganic thickeners selected from talc, graphite and Group I, II and IV metal oxides and carbonates.
However, the grease compositions embodying these thickening agents typically fail in prolonged or excessive service of storage. Further, the metal salts in bearing systems used in the prior art can be corrosive to the metallurgical entities and can cause stress cracking in plastic bearings. In addition, the mineral diatoms are frequently hygroscopic and can induce hydrolytic breakdown of the oil base and undergo bleed-out, a phenomena whereby the physical saturation or absorption changes under bearing stress. Polyethylene, while substantially resistant to hydrolytic reaction, undergoes slow but relentless oxidation and crystallization under frictional wear and stress. In addition, grease containing asbestos fibers may be abrasive. Many of the thickeners used may also increase the toxicity of the lubricant within which it is used, thereby restricting its possible commercial applications.
Furthermore, many current grease-type lubricants are generally inoperable over a wide temperature range, especially at extreme low temperatures, and are thus not completely suitable for many potential commercial or military applications. For example, where lubricants do not possess physical characteristics which will permit their successful and reliable operation in equipment at extremely low temperatures, serious operational problems are introduced which often necessitates the use of auxiliary heaters to raise ambient temperatures.
Another problem with many present lubricants is their corrosiveness and stability to oxidation. It is known that if the lubricant contains dissolved air or moisture, its corrosiveness greatly increases. If such corrosive lubricants are used, the life of the part containing them is significantly shortened. The stability of the lubricant to oxidation is also extremely important: if such stability is low, the useful properties of the lubricant will be negatively affected. Randisi, U.S. Pat. No. 4,396,516 describes an improved lubricating composition and method for making it. However, the present invention provides for the composition with the different ingredients and method, allowing to make the composition with the oxidation resistance of about 50% higher than that of the composition of the U.S. Pat. No. 4,396,516, compression load and shear load capabilities of about 10% higher than that of the composition of said patent, and other valuable properties which will be seen from the description and claims below.
It is an additional object of this invention to provide a lubricant with a low toxicity and significantly extended shelf life.
It is still another object of this invention to provide a lubricating composition which would be able to withstand extreme compression of contacting moving parts.
The aforesaid as well as, other objects and advantages will be made more apparent in reading the following description and the adjoined claims.